1. Field of the invention
The present invention relates to a network of transceivers which monitor a defined geographic area for the receipt of transmissions indicative of emergency situations, and which relay an alarm signal to a central station for appropriate action. More particularly, the present invention is directed to an improved portable transmitter for such transceiver networks wherein false alarms are inhibited by limiting the transmitter to a single use within a predetermined time period.
2. Description of the Prior Art
Emergency transmitter systems are known in the art. U.S. Pat. No. 4,998,095, which issued to N. G. Shields on Mar. 5, 1991, describes an emergency transmitter system for individuals within a predetermined geographic area such as a campus, shopping mall, or stadium. A plurality of fixed transceivers at selected locations in the area monitor radio frequency emergency transmissions from portable transmitters. To avoid false alarms, Shields provides a single-use portable transmitter that requires a reset by security personel. The requirement for reset would be an inconvenience, necessitating the user to travel to the security office for reset. Also, if the security office is not open at the time, as might likely be the situation if a reset was required between closing on Friday evening and re-opening on Monday morning, there would be an extended time period when the user was unprotected.